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      <title>在高并发场景下如何提高 Zookeeper 的吞吐量和响应时间？ - 交互式测验</title>
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            <div class="quiz-header">
              <h1>在高并发场景下如何提高 Zookeeper 的吞吐量和响应时间？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
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  {
    "question": "根据文档，在对ZooKeeper进行JVM调优时，除了增加堆内存（Heap Size）外，还建议采用哪种策略来优化垃圾回收（GC）？",
    "options": [
      "完全禁用垃圾回收以避免性能抖动。",
      "总是使用JVM默认的垃圾回收器，因为它最稳定。",
      "考虑使用G1GC或CMS等垃圾回收策略，以减少GC频率和停顿时间。",
      "减小堆内存以强制频繁进行GC，从而释放内存。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确指出，优化垃圾回收（GC）参数可以减少GC频率。具体建议是考虑使用G1GC（Garbage-First Garbage Collector）或CMS（Concurrent Mark-Sweep）作为垃圾回收策略，并给出了相应的配置示例，旨在在高负载下保持系统响应的稳定性。",
    "source": "文档中「1.1 调整 JVM 参数」部分",
    "hint": "文档中提到了两种具体的垃圾回收器名称作为优化建议。"
  },
  {
    "question": "在ZooKeeper集群配置中，为什么通常建议节点的数量为奇数？",
    "options": [
      "奇数个节点可以获得更好的网络吞吐量。",
      "这是为了简化客户端的连接逻辑。",
      "为了在发生网络分区时，能够形成一个拥有“过半”多数的群体，从而保证选举和决策的一致性。",
      "偶数个节点在进行数据同步时会产生额外的开销。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档提到，ZooKeeper集群的节点数量应为奇数，是为了“确保故障恢复和选举的一致性”。这是因为ZooKeeper的选举算法（Zab协议）要求集群中存活的节点必须超过半数才能对外提供服务。在一个奇数成员的集群中（如3个、5个），它能容忍的故障节点数比邻近的偶数成员集群要多，从而更容易形成多数派，避免“脑裂”问题。",
    "source": "文档中「2.1 增加集群节点」部分",
    "hint": "思考一下分布式系统中的“过半机制”或“多数派原则”在故障恢复和选举中的作用。"
  },
  {
    "question": "调整`tickTime`参数是ZooKeeper性能调优的一种方式。减小`tickTime`的值可能会带来什么影响？",
    "options": [
      "显著增加系统的存储开销。",
      "降低客户端响应时间，但可能会增加网络负担。",
      "只影响Leader节点的选举速度，对客户端请求无影响。",
      "提高系统的响应时间，同时减少网络负担。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "`tickTime`是ZooKeeper中的基本时间单元，用于控制心跳和会话超时。文档指出，减小`tickTime`可以降低响应时间（因为心跳和超时检测更频繁），但这样做的代价是增加了节点间的心跳通信频率，从而可能增加整体的网络负担。",
    "source": "文档中「1.2 调整 Zookeeper 配置参数」部分",
    "hint": "文档中提到了`tickTime`调整后，对“响应时间”和“网络负担”的双重影响。"
  },
  {
    "question": "在优化与ZooKeeper交互的客户端时，文档推荐了哪种方法来减少因频繁建立和关闭连接而产生的开销？",
    "options": [
      "为每个请求创建一个新的连接以保证隔离性。",
      "增加客户端的会话超时时间。",
      "使用连接池技术来复用和管理连接。",
      "在客户端进行数据缓存，减少对ZooKeeper的访问。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在“优化客户端”一章中明确建议“使用连接池技术，避免频繁的建立和关闭连接，减少连接的开销”。连接池可以维护一组已经建立好的连接，客户端需要时直接从中获取，使用完毕后归还，从而显著提高了效率和性能。",
    "source": "文档中「3.1 使用连接池」部分",
    "hint": "思考一下在数据库访问等场景中，我们通常如何管理和复用昂贵的连接资源。"
  },
  {
    "question": "关于ZooKeeper的Watcher机制，以下哪个描述最符合文档的建议？",
    "options": [
      "Watcher机制比轮询更消耗服务端资源，应尽量避免使用。",
      "应结合频繁的轮询操作来确保Watcher通知的可靠性。",
      "Watcher是一种被动接收通知的机制，比主动轮询更能减少不必要的网络通信。",
      "Watcher通知是同步阻塞的，会严重影响客户端性能。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档的核心建议是“合理使用Watcher机制来监控节点的变化，而不是频繁地进行轮询操作，减少不必要的网络通信”。这说明Watcher机制是一种高效的事件通知模型，客户端只需注册一次监听，当数据变化时服务端会主动通知客户端，避免了客户端不断发起无效的查询请求，从而节约了网络和CPU资源。",
    "source": "文档中「7. 利用 ZooKeeper 的 Watcher 机制」部分",
    "hint": "文档将Watcher机制与“频繁地进行轮询操作”进行了对比，强调了其在减少网络通信方面的优势。"
  },
  {
    "question": "根据文档，以下哪项**不**是推荐的ZooKeeper性能优化策略？",
    "options": [
      "将多个写操作合并成一个批量请求进行提交。",
      "将ZooKeeper节点部署在专用的网络环境中以避免干扰。",
      "在ZooKeeper内部启用原生的数据分片功能来分散数据负载。",
      "定期升级ZooKeeper到最新版本以获取性能改进。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在“配置适当的分片和副本”部分明确指出：“虽然Zookeeper本身不支持数据分片，但可以通过合理配置数据结构和客户端负载均衡来减少单个节点的负担。” 这意味着启用原生数据分片不是一个可行的选项。而批量操作、网络隔离和升级版本都是文档中明确推荐的优化策略。",
    "source": "文档中「2.2 配置适当的分片和副本」部分 (以及其他相关部分)",
    "hint": "请仔细阅读文档中关于“数据分片”的描述，看看它提到了什么限制。"
  },
  {
    "question": "在调整ZooKeeper的数据结构以优化性能时，文档提出了什么建议？",
    "options": [
      "尽可能创建深层次的节点结构，以便于管理。",
      "在节点中存储大量的数据，以减少节点总数。",
      "尽量减少节点的总体数量，并避免创建过多的临时和无用节点。",
      "频繁创建和删除临时节点来测试集群的稳定性。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在“调整数据结构”一节中给出了两点核心建议：一是“尽量减少 Zookeeper 节点的数量”，二是“避免过多的临时节点和无用节点”。过多的znode会增加ZooKeeper内存的负担和数据同步的复杂性，从而影响整体性能。",
    "source": "文档中「6. 调整数据结构」部分",
    "hint": "该部分的两个小标题“减少节点数量”和“使用适当的数据结构”直接指明了优化的方向。"
  }
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                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  